From: Paolo Valente <paolo.valente@linaro.org>
To: Jens Axboe <axboe@kernel.dk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
Angelo Ruocco <angeloruocco90@gmail.com>,
Dennis Zhou <dennis@kernel.org>,
Josef Bacik <josef@toxicpanda.com>,
Liu Bo <bo.liu@linux.alibaba.com>,
Bart Van Assche <bvanassche@acm.org>,
Johannes Weiner <hannes@cmpxchg.org>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
ulf.hansson@linaro.org, linus.walleij@linaro.org,
broonie@kernel.org, bfq-iosched@googlegroups.com,
oleksandr@natalenko.name, cgroups@vger.kernel.org,
linux-doc@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
Paolo Valente <paolo.valente@linaro.org>
Subject: [PATCH 00/12] unify the interface of the proportional-share policy in blkio/io
Date: Mon, 12 Nov 2018 10:56:20 +0100 [thread overview]
Message-ID: <20181112095632.69114-1-paolo.valente@linaro.org> (raw)
Hi Jens, Tejun, all,
about nine months ago, we agreed on a solution for unifying the
interface of the proportional-share policy in blkio/io [1]. Angelo
and I finally completed it. Let me briefly recall the problem and the
solution.
The current implementation of cgroups doesn't allow two or more
entities, e.g., I/O schedulers, to share the same files. So, if CFQ
creates its files for the proportional-share policy, such as, e.g,
weight files for blkio/io groups, BFQ cannot attach somehow to them.
Thus, to enable people to set group weights with BFQ, I resorted to
making BFQ create its own version of these common files, by prepending
a bfq prefix.
Actually, no legacy code uses these different names, or is likely to
do so. Having these two sets of names is simply a source of
confusion, as pointed out also, e.g., by Lennart Poettering (CCed
here), and acknowledged by Tejun [2].
In [1] we agreed on a solution that solves this problem, by actually
making it possible to share cgroups files. Both writing to and
reading from a shared file trigger the appropriate operation for each
of the entities that share the file. In particular, in case of
reading,
- if all entities produce the same output, the this common output is
shown only once;
- if the outputs differ, then every per-entity output is shown,
preceded by the name of the entity that produced that output.
With this solution, legacy code that, e.g., sets group weights, just
works, regardless of the I/O scheduler actually implementing
proportional share.
But note that this extension is not restricted to only blkio/io. The
general group interface now enables files to be shared among multiple
entities of any kind.
(I have also added a patch to fix some clerical errors in bfq doc,
which I found while making the latter consistent with the new
interface.)
Thanks,
Paolo
[1] https://lkml.org/lkml/2018/1/4/667
[2] https://github.com/systemd/systemd/issues/7057
Angelo Ruocco (7):
kernfs: add function to find kernfs_node without increasing ref
counter
cgroup: link cftypes of the same subsystem with the same name
cgroup: add owner name to cftypes
block, bfq: align min and default weights with cfq
cgroup: make all functions of all cftypes be invoked
block, cfq: allow cgroup files to be shared
block, throttle: allow sharing cgroup statistic files
Paolo Valente (5):
cgroup: add hook seq_show_cft with also the owning cftype as parameter
block, cgroup: pass cftype to functions that need to use it
block, bfq: use standard file names for the proportional-share policy
doc, bfq-iosched: fix a few clerical errors
doc, bfq-iosched: make it consistent with the new cgroup interface
Documentation/block/bfq-iosched.txt | 31 +++--
block/bfq-cgroup.c | 148 +++++++++++++-------
block/bfq-iosched.h | 4 +-
block/blk-cgroup.c | 22 +--
block/blk-throttle.c | 24 ++--
block/cfq-iosched.c | 105 +++++++++++----
fs/kernfs/dir.c | 13 ++
include/linux/blk-cgroup.h | 10 +-
include/linux/cgroup-defs.h | 14 +-
include/linux/cgroup.h | 13 ++
include/linux/kernfs.h | 7 +
kernel/cgroup/cgroup.c | 262 +++++++++++++++++++++++++++++-------
12 files changed, 483 insertions(+), 170 deletions(-)
--
2.16.1
next reply other threads:[~2018-11-12 9:57 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-12 9:56 Paolo Valente [this message]
2018-11-12 9:56 ` [PATCH 01/12] kernfs: add function to find kernfs_node without increasing ref counter Paolo Valente
2018-11-12 12:28 ` Greg Kroah-Hartman
2018-11-13 1:56 ` Matthew Wilcox
2018-11-13 17:53 ` Paolo Valente
2018-11-13 19:35 ` Greg Kroah-Hartman
2018-11-12 9:56 ` [PATCH 02/12] cgroup: add hook seq_show_cft with also the owning cftype as parameter Paolo Valente
2018-11-12 9:56 ` [PATCH 03/12] block, cgroup: pass cftype to functions that need to use it Paolo Valente
2018-11-12 9:56 ` [PATCH 04/12] cgroup: link cftypes of the same subsystem with the same name Paolo Valente
2018-11-12 9:56 ` [PATCH 05/12] cgroup: add owner name to cftypes Paolo Valente
2018-11-12 9:56 ` [PATCH 06/12] block, bfq: align min and default weights with cfq Paolo Valente
2018-11-12 9:56 ` [PATCH 07/12] cgroup: make all functions of all cftypes be invoked Paolo Valente
2018-11-12 9:56 ` [PATCH 08/12] block, cfq: allow cgroup files to be shared Paolo Valente
2018-11-12 9:56 ` [PATCH 09/12] block, bfq: use standard file names for the proportional-share policy Paolo Valente
2018-11-12 9:56 ` [PATCH 10/12] block, throttle: allow sharing cgroup statistic files Paolo Valente
2018-11-12 9:56 ` [PATCH 11/12] doc, bfq-iosched: fix a few clerical errors Paolo Valente
2018-11-12 9:56 ` [PATCH 12/12] doc, bfq-iosched: make it consistent with the new cgroup interface Paolo Valente
2018-11-12 9:58 ` [PATCH 00/12] unify the interface of the proportional-share policy in blkio/io Paolo Valente
2018-11-12 10:00 ` Oleksandr Natalenko
2018-11-12 10:14 ` Oleksandr Natalenko
2018-11-12 10:17 ` Paolo Valente
2018-11-12 15:35 ` Jens Axboe
2018-11-12 15:45 ` Paolo Valente
2018-11-12 15:48 ` Jens Axboe
2018-11-12 15:54 ` Josef Bacik
2018-11-12 16:05 ` Jens Axboe
2018-11-15 11:54 ` Angelo Ruocco
[not found] ` <CADiTV-3tSpEMG7EHz3XGvfekNdtN8k_KQiDMtyykgOb81cvO0g@mail.gmail.com>
2018-11-15 15:42 ` Oleksandr Natalenko
2018-11-15 16:30 ` Jens Axboe
2018-11-19 9:46 ` Angelo Ruocco
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